Method of making printing screens



ii; 30, 194. D. B. NOLAND Em;

METHOD OF MAKING A PRINTING SCREEN Filed March 27, 1959 Javidfi Mama g YY the same.

away to expose the screen embedded therein; ing, etc. any metals, suchas zinc, aluminum,

Patented June 30,1942 2,288,0205

UNITED STATES ENT orFICE f METHOD OF MAKING PRINTING SCREENS:

David B. Noland and Murray 1.. Loam,

Nashville, Tenn.

Application March at; 1939, Serial No. 264,438

This invention relates to a metallic printing in Fig. 1; Fig. 3, anenlarged transve'rsesecscreen and to the method or methods of makingtional view, the section being taken .as' indicated at line 8 of Fig.1;v and Fig. 4, a plan In the commercial printing practice as emview ofa printing screen. embodying .our'inployed today, silk or metal screensare provided vention. with a gelatin material or other protective ma- Inthe practice of our invention, we select 'a -terial which blocks outareas of the screen screen In whichls not affected or only slightlythrough which coloring material is not passed, aflected by aselectedmordant, and impregnate those portions of the screen which areleft open the S en th ou hly with a metal foil which for the printing ofcolors serving to form the 1 is readily attacked by the mordant, themetal design. Onemajor difllcultyis the relatively foil being indicatedby the-numeral II. short life afforded by the glue or gelatin. -An-Suitable method for pp y n th metal foil to other objection is theJagged lines or irregular the screen and incorporating it therewith maylines and pinholing around the, edgesof the dee emp oyed. If des red, asheet of metal foil M sign and over'the entire screen due to the break-II. as illustrated in Fig. 2, may be placed upon ing out of the gelatinfiller from the openings in the screen and the screen with the foilsheets the supporting screen. This necessitates stop.- is then passedbetween c mpacting rollers ping production to repair or exchangescreens. which press the metal foil about the screen Another objectionis the oil soaking and swelling and incorporate it so firmly therewiththat it oi the gelatin layer. A further objection is the issubstantially integral in eifect. The result fact that this type ofscreen is limited to cerl c mposite, metal plate in which the metal tainkinds and types of paint, paste, and ink me- 'foil becomes asubstantially integral part there-. diums and vehicles, used. It i alsofound that 01 with the screen embedded in the metal.

with this type of screen, there is premature wear The screen is-preferably located inthe up r when the scren is forced onto irregularshapes D the m ll-m P ate 0 hat there is left and surfaces being rinted,belowthescreen aspace which is substantially An object of the presentinvention is to overequal, to the entire thickness oi the plate lesscome the above dlflficulties, to provide a metal the hi n s of thescreen. us e w screen which has a long life and which enables he screens in iving a sharp separation, as a sharp reproduction to be obtained,avoiding 80 will be later d scribedpinholes, etc. .A further object i toprovide an f th omposite plate is completed, vwe all-metal screen inwhich the protecting or e 8 P e u e S milar to that used in the blockingareas are formed of metal which 1 production of half-tone intaglioplates. The, pregnates the screen and is integrally formed mpos e pla eis treated, sensitized, e p sed therewith, the design being sharplyformed as with the desired s n. developed. made rethrough the etching ofthe metal blocking area, sistant to an etching mordant, and then exposedwithout etching of the screen. Another object to he e ching process. Theselected mordant is to provide a simple and efiective method for l ackreadily the metal filler, leaving only forming an all-metal screen,wherein a screen h ly a ta ked the screen structure. The deof one metalimpregnated t a metal 1 11, 40 sired design is etched through the metalfiller the metal foil being etched through by 9, m and the-resultantscreen is stretched on a spedant which does not substantially attack orcial frame and tested.- The Joint formed by th merely slightly attacksthe nu screen screen and the edge of the frame'is then sealed Otherspecific objectsand advantages will apwi h pap ape 80' as o form a wellfor the pear as the specification proceeds. Printing ks pastes t t areused. The sub- The invention is illustrated, in a preferred lect is p ined from the bottom of the resultant embodiment, by th accompanyingdrawingyin screen v which- The metal used for the wire screen and theFigure 1 is a view of a composite metal plate metal used .for the fillermay be selected from with a screen embedded therein which is em- 9.number of available materials. The two ployed prior to the forming ofthe printing metals forming the composite sheet may be comscreen, thecentral part of the plate being cut bined by either dipping, rolling,spraying, scrap- Fig. 2, a metal foil sheet which is placed on thesolder, or alloys, or similar metals into the mesh screen for formingthe composite plate shown 58 of a bronze, copper, Monel, stainlesssteel, steel,

sultant plate is then the light penetrates the negative,

etc., or alloys of metal mesh, and thickness, so as to completely coverscreen or wire cloth. The important require- 7 1 ment is that the screennot be affected by the mordant which is used for etching the filler.For-example, a wire screen of cloth or bronze or other metals may beused in combination with a foil or filler of zinc, aluminum,copper, oralloys of these and other metals. In combining ithe light does notcontact the solution or and fill the entire openings or meshes of the vfiller with the screen, a number of methods may be used. Pressing thefoil about the wire"=, is effective in that it produces a smoothsurface,

free of blemishes, with the screen structure em}- bedded therein andpreferably on the top side of the sheet The composite sheet can also bemade by spraying the metal filler on to the wire y rolled to give thesmooth surface desired. Another method is to coat the wire mesh on oneside with a metallic paint ofthe process known as metalizing. Theeelectrolytic conductance properties. The coated screen .is then platedthrough the wire screen by the electrolytic process. The metallic paintis stripped off andthe plated screen, if necessary, rolled to give thesmooth surface desired.

It isobvious that many other methods may be The principal propertydesired and obtained in the composite sheet or plate is the intricatebond between the wire screen and the material used as a filler and theresultant smooth'surfaces on the sheet. It is necessary that the wiremesh be embedded and locked in the foil, the

' sprayed metal, or the plating, etc. A definite thickness of metalexists beneath the wire screen and the outside or bottom in thethickness of the composite material and the thickness of the embeddedwire screen. It is foil surface. This .thiclmess of metal issubstantially the difference an important factor that contributestothe'clean,

sharp lines of the printed design because after the printing inks orpastes have been forced through the open screen of the design, they have1 space to heal the break caused by the screen. This thickness of metalenables a smooth, uniform deposit of ink or paste to be made whenprinting. It also helps control the thickness of the application whichgives a heavyvor thin covplate is laid on a suitable cloth of thedesired weave,

opaque portion of the negative, the solution is unexposed. Then themetal is covered with a thin coating of etching ink or similar materialand then placed under a stream of running water which washes away theink and solution from the unexposed portion of the solution, leaving thedesign showing with the bare metal exposed where the light did' notcontact or under the opaque portion of the negative. After the solutionis completely developed, dry off with a channels by blotting the surfacesoftly. The surface is then covered with 'a coating of dry dragon'sblood, asphaltum,"or rosin, or any of the well known etching or toppingpowders and then the surface is brushed lightly so as to brush all' ofthe excess 1 dragon's blood of! of the clean portion of the metal.taking care' to leave a generousamount clinging tothe etchingink- Thisisthen placed in an oven orcan'be held over an open flame face up untilthe powder has melted and sealed all small pinholes and around the edgesof the designso that the etching mordant cannot etch away the originalsharpness of the design. The back side of-the metal. blocked out. with asuitable. material, such as asphaltum, rosin, shellac, .or. lacquer, soas to have no metal showing,- This' j is then dried and tacked on asuitable frame;

is then painted or It is now ready for etching.

The design can also be obtained stems; or laying the design with anyacid resisting mew, I terial so as to leave the portion of. the screenwhich is required to print'unpain'ted'and then backed up or blocked outon the back side in the j regular way. Or by a previously sensitised andexposed sheet of gelatin or carbon tissue which is laid upon the metaland then squeegeed into place in such a manner as to getanacid-realstin: background.

The composite metal a suitable container containing a suitable etchingmordant. A mordsnt for etching aluminum interlocked with bronze wire isone part nitric, one-half part iron chloride, 40 Baum, two parts. water,one-half part saturated solution gum 'arabic, the strength'depending onthe weather and on the type of metal being etchedaway from thescreen andthe kind of screen being used; A

albumen ammonium bichromate sensitizing so-:

lution' or any of the well known copper or zinc plate coating solutionsknown to the photo-engraying trade as cold top enamel. This is thenplaced in the whirler in a dark room and whirled.

and heated at the same time, taking care to get a smooth, even coatingover the entire surface. As soon as the solution becomes dry, an opaquenegative of the regular type or opaque drawing is laid with the faceside of the negative or drawing in contact with the solution side of themetal and exposed to a carbon arc-light for seven minutes which sets upthe solution where mordant consisting of 2% nitric acid solution issuitable for etching zinc interlocked with bronze After the mordant orstainless steel or steel. has etched away the metal so that the screencan be seen from the face side, it is then removed from the etching bathand dried off,

then reheated soas to'remelt the protecting etching ink and dragon'sblood over the edges of the design so as to hold them sharp and preventundercutting of the design. It is then replaced in the etching bath andwith a small amount of agitation will soon etch all of the remainingmetal from between the meshes of the wire screen. or cloth. Asv soon asthe etching.

action has stopped, the'screeos should be removed from the etchingbathand rinsed of! with clear water, dried, and the protective backing andetching ink removed with gasoline or similar solvents and removed fromthe etching frame.

The screen is then placed on a suitable frame with the face sideopposite the frame. The frame should be of the stretcher type on whichthe screen can be stretched at any given point. After all the slack hasbeen removed and the screen stretched reasonably tight, it is ready forand where the use in the usual way.

under the screenisthenplacedin.

material, such as asphalt By incorporating only one sheet of foil withthe wire cloth, we are able to term the wire on one side with the tollmaterial on the other, the i'oil metal, however, penetrating between theopenings in the wire cloth and forming on the other side a smooth evensurface, with, however, a part of the wire cloth surface being visible.Other methods 01' impregnating the cloth may be used, as before stated.

The mordant described slightly aflects the screen, but because oi thefact that the wire side of the screen is blocked 01! with a suitabledoes not have much opp rtunity to attack the screen. Since the etchingis done (mm the metal foil side of the Wire. the plate is etched about35% through before the mordant comes in contact with the wire'screen.From this point, the

filler metal is attacked by the mordant 'at so muchsreater rate or speedthan is-the wire screen that. there is verylittle or no eflect on-:thescreem The new screen has a decided advantage overthesilkscreeninthatitlgidsitselireadilyto be pre-tormed so as to conformto irregular shapes and surfaces. pre-forminzis practical, unusualstress and strain on the screen is avoided; a The results obtained withthem'etallic tainable under tm same conditions.

'ture and atmcspherlcconditiocis dofnot ectetc., the mordant the newscreen. A areatervariety of inks, paints,

' and pastes may be employed without affecting the filler.

While in the ioregoing descriptiom we have set i iorth certain specificexamples, it will be 'understood that such examples may be omitted andwell known equivalents substituted therefor, and

known practice and without departing from the spirit of our invention.We wish it to beunderstood that'we do not desire to be limited to theexact details oi construc- 7 tion shown and described, for obviousmodifie tionswilloccurtoaperson'skilledintheam- We claim:

1. a method a forming a printing screen, com

imp esnatins a wire screen or bronze I with aluminum i'oil, forming aprotective thermoplastic layer about said ioijl, etching the comtheprotective layer, and then sameinthemrdant bath whileaaitatlnsthefl'bath.

2. A method ionizing a prin acreen,-

ting a metal wire 1, of a diflerent metal, forminza protectithermoplastic layer about filler metal, etching the cote sheet with amozdggt for said mam filler, drying the plate.

in the mordant s tag-11:11; the protective layer.

